J/A+A/620/A127 Classification of RR Lyrae and Cepheid (Molnar+, 2018)
Gaia Data Release 2: Validating the classification of RR Lyrae and Cepheid
variables with the Kepler and K2 missions.
Molnar L., Plachy E., Juhasz L.A., Rimoldini L.
<Astron. Astrophys. 620, A127 (2018)>
=2018A&A...620A.127M 2018A&A...620A.127M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; MK spectral classification
Keywords: stars: variables: general - stars: variables: RR Lyrae -
stars: variables: Cepheids
Abstract:
The second data release of the Gaia mission (DR2) includes an advance
catalogue of variable stars. The classifications of these stars are
based on sparse photometry from the first 22 months of the mission.
We set out to investigate the purity and completeness of the all-sky
Gaia classification results with the help of the continuous light
curves of the observed targets from the Kepler and K2 missions,
focusing specifically on RR Lyrae and Cepheid pulsators, outside the
Galactic bulge region.
We cross-matched the Gaia identifications with the observations
collected by the Kepler space telescope. We inspected the light curves
visually, then calculated the relative Fourier coefficients and period
ratios for the single- and double-mode K2 RR Lyrae stars to further
classify them.
We identified 1443 and 41 stars classified as RR Lyrae or Cepheid
variables in Gaia DR2 in the targeted observations of the two missions
and 263 more RR Lyre targets in the full-frame images (FFI) of the
original mission. We provide the cross-match of these sources. We
conclude that the RR Lyrae catalogue has a completeness between
70-78%, and provide a purity estimate of between 92-98% (targeted
observations) with lower limits of 75% (FFI stars) and 51% (K2
worst-case scenario). The low number of Cepheids prevents us from
drawing detailed conclusions, but the purity of the DR2 sample is
estimated to be about 66%.
Description:
Cross-match of the sources in common between Gaia DR2 RR Lyrae and
Cepheid classifications and the Kepler (original mission) and K2
observations (between Campaigns 0-13). Table A1 lists all RRab and RRc
stars from the original mission. A4 and A5 lists the RRab and RRc
stars from the K2 mission, respectively. Columns are: Gaia DR2
identifier, DR2 RA and Dec coordinates, G-band brightness in
magnitudes, classification in the DR2 all-sky variability survey the
KIC or EPIC identification, the flux-calibrated Kp brightness in
magnitudes. The last column is the data type for the original mission
(Target Pixel File or Full-Frame Image photometry). For the K2
mission, the pulsation period is listed in the last column. Details of
the DR2 all-sky variability survey are published by Holl et al.
(2018A&A...618A..30H 2018A&A...618A..30H).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 77 185 Kepler-Gaia DR2 RR Lyrae crossmatch (kepg2rrl.dat)
tablea2.dat 77 27 Cross-match of RRc-type stars in the
original Kepler observations
tablea3.dat 85 18 Stars with uncertain but likely classifications
from the original Kepler observations
tablea4.dat 86 1211 K2-Gaia DR2 RRab crossmatch (k2g2rrab.dat)
tablea5.dat 86 142 K2-Gaia DR2 RRc crossmatch (k2g2rrc.dat)
tablea6.dat 91 18 Cross-match of RRd-type stars in the
K2 observations
tablea7.dat 96 27 Cepheid cross-match
tablea8.dat 92 24 Cross-match of stars that turned out not to be
RR Lyrae stars
tablea9.dat 90 15 Cross-match of stars that turned out not to be
Cepheid variables
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/MNRAS/456/2260 : K2 Variability Catalogue II (Armstrong+, 2016)
J/A+A/620/A128 : Gaia DR2 study of Herbig Ae/Be stars (Vioque+, 2018)
Byte-by-byte Description of file: tablea[123].dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Gaia DR2 source identifier (source_id)
21- 31 F11.7 deg RAdeg Gaia DR2 Right Ascension (ICRS) at Ep=2015.5
33- 42 F10.7 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
44- 49 F6.3 mag Gmag Gaia DR2 median G-band magnitude
51- 54 A4 --- VClass Gaia DR2 best variable class
56- 63 I8 --- KIC Kepler Input Catalog identifier
65- 70 F6.3 mag Kpmag ?=- Flux-calibrated Kepler magnitude
72- 77 A6 --- Type [FFI target] Kepler data type (target or FFI)
79- 86 A8 --- KpClass Kepler class (only in tablea3.dat)
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Byte-by-byte Description of file: tablea[45].dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Gaia DR2 source identifier (source_id)
21- 31 F11.7 deg RAdeg Gaia DR2 Right Ascension (ICRS) at Ep=2015.5
33- 43 F11.7 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
45- 50 F6.3 mag Gmag Gaia DR2 median G-band magnitude
(medianmagg_fov)
52- 55 A4 --- VClass Gaia DR2 best variable class (bestclassname)
57- 65 A9 --- EPIC K2 Ecliptic Plane Input Catalog identifier
67- 71 A5 --- K2C Observing K2 campaign
73- 78 F6.3 mag Kpmag Flux-calibrated Kepler magnitude
80- 86 F7.5 d Per Pulsation period
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Byte-by-byte Description of file: tablea6.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Gaia DR2 source identifier (source_id)
21- 31 F11.7 deg RAdeg Gaia DR2 Right Ascension (ICRS) at Ep=2015.5
33- 43 F11.7 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
45- 50 F6.3 mag Gmag Gaia DR2 median G-band magnitude
52- 55 A4 --- VClass Gaia DR2 best variable class
57- 65 I9 --- EPIC K2 Ecliptic Plane Input Catalog identifier
67- 68 I2 --- K2C Observing K2 campaign
70- 75 F6.3 mag Kpmag Kepler magnitude
77- 83 F7.5 d P0 Fundamental pulsation period
85- 91 F7.5 d P1 First overtone pulsation period
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Byte-by-byte Description of file: tablea7.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Gaia DR2 source identifier (source_id)
21- 31 F11.7 deg RAdeg Gaia DR2 Right Ascension (ICRS) at Ep=2015.5
33- 43 F11.7 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
45- 50 F6.3 mag Gmag Gaia DR2 median G-band magnitude
52- 56 A5 --- VClass Gaia DR2 best variable class
58- 66 I9 --- KIC/EPIC K2 Ecliptic Plane Input Catalog identifier
or Kepler Input Catalog identifier
68- 73 A6 --- Campaign Campaign
76- 94 A19 --- ID Other name
96 A1 --- Note [ABC] Note (1)
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Note (1): Note as follows:
A = Kepler field
B = clear identifications in the K2 fields
C = uncertain identifications
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Byte-by-byte Description of file: tablea[89].dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Gaia DR2 source identifier (source_id)
21- 31 F11.7 deg RAdeg Gaia DR2 Right Ascension (ICRS) at Ep=2015.5
33- 43 F11.7 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
45- 50 F6.3 mag Gmag Gaia DR2 median G-band magnitude
52- 56 A5 --- VClass Gaia DR2 best variable class
58- 66 I9 --- EPIC K2 Ecliptic Plane Input Catalog identifier
68- 73 A6 --- K2C Observing K2 campaign
75-104 A30 --- Com Comment Alternative identifications and/or
likely variability class, if possible
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Acknowledgements:
Laszlo Molnar, molnar.laszlo(at)csfk.mta.hu
History:
07-Dec-2018: tables A1, A4 and A5
22-Jan-2020: tables A2, A3, A6, A7, A8 and A9 added
(End) Patricia Vannier [CDS] 05-Dec-2018